The present invention relates in general to liquid flow monitoring and flow control devices, and more particularly to a system for monitoring the drip rate in an intravenous infusion apparatus and to apparatus for setting the drip rate of such intravenous infusion apparatus.
The general purpose of the intravenous flow rate counter apparatus is to measure and display the rate and volume of the flow of liquids being infused into a patient intravenously, to sense the presence or absence of a liquid drop and to electronically convert this presence or absence into both audible and visual information to assist the medical personnel to adjust the intravenous infusion apparatus to match the infusion rate prescribed by the treating physician. It is a purpose of the system to also monitor the total volume of liquid infused into the patient intravenously by use of a digital display, to warn the patient and/or the medical personnel if a blockage of the flow of the liquid into the patient has occurred. It allows the medical personnel to monitor the operation of the intravenous infusion apparatus at a distance and in a darkened room, and advises medical personnel when a given amount of fluid has been infused so that additional fluid or medication can be added to the intravenous solution.
The usual medical procedure for gradual intravenous introduction of fluids into the human body, such as liquid nutrients and medication, makes use of an apparatus commonly referred to as an Intravenous Set, hereinafter generally referred to as an "IV". This IV set is comprised of a container of fluid, normally supported in an inverted position, a valve mechanism which allows the fluid to drip out of the container at a controlled rate into a drip chamber below the container and a tube leading from the bottom of the drip chamber. The tube has a needle at its end which is inserted into the vein of the patient, allowing the fluid to flow into the patient. The drip chamber serves a dual function; it allows a nurse or other medical personnel to observe the rate at which the fluid drips out of the bottle, and it serves as a reservoir for the fluid at the lower end of the chamber to insure that no air enters the main feeding tube leading to the patient.
While observation of the rate of flow via the drip chamber as a simple and effective way of controlling the amount of fluid fed into a patient over a period of time, its ultimate effectiveness requires that a relatively constant vigil be maintained over the drop flow. Otherwise, the patient's movements may cause the tube to become restricted, cutting off the flow of the fluids, the nurse may infuse an amount into the patient greater or at a faster rate than that called for by the physician's orders, or the supply of fluid into the bottle may become exhausted. It has been the general practice in hospitals to have nurses periodically monitor drop flow rates at each intravenous station, which is a tedious and time-consuming process, prone to error, with associated, possibly serious, consequences. It results in a substantial reduction of the available time of qualified medical personnel for other important duties. Typically, the nurse monitoring the drop flow rate will use a watch to time the number of drops flowing in an interval of one or more minutes, and will then mentally perform the mathematics necessary to convert the timed drop count to an appropriate rate, for example in cubic centimeters or milliliters per hour. If the calculated flow rate is substantially different from the prescribed rate, the nurse must manually adjust the tubing restriction device for a new rate, count drops again, and recalculate to measure the new rate. Obviously each of these described measurements and calculations and flow rate adjustments usually takes several minutes of time which, when multiplied by the number of stations being monitored and the number of times each station is monitored per day, can result in a substantial percentage of total personnel time available. Also, due to the pressure of other matters, the mental calculations performed by the nurse may not always prove to be reliable. This situation is compounded when the treating physician orders that additional medication be added to the IV fluid after a certain amount has been infused. Because of the importance of being able to accurately see or visually observe the drops of almost transparent liquid falling into the drip chamber to monitor the drip rate by this typical method, obviously the monitoring must be done in a lighted area.
An object of the present embodiment of this invention, therefore, is the provision of intravenous flow rate counter apparatus which optically monitors the drops of a liquid decending in the drip chamber of a conventional intravenous infusion set, by optically sensing the presence or absence of the liquid drop and electronically converting the data into both audible and visual information forms and visually informs the monitoring nurse of the existing drip rate, enabling the nurse or other monitoring personnel to promptly detect departures from the prescribed rate and adjust the device to the specified rate. This device does not influence or control either the drop rate or the volume of the liquid being administered to the patient, as these always remain strictly under the manual control of the nurse or other supervising personnel. An optical sensing head and its associated electronic circuitry is attached to and secured to any of the drip chambers of the standard types presently available, and is connected via a flexible electrical multiconductor cord to a battery and audible alarm box, which also includes electronic sensing circuitry for detection of No-Drop conditions. A display unit connected to this optical sensing head and battery and audible alarm box contains two displays of 4-digits each, one displaying the infused volume number in milliliters (ml) and the other the Check Point Volume in milliliters, and additionally includes a visual alarm and an audible alarm of different tone and pitch from that of the previously mentioned battery and alarm box, and also includes associated switches for digit setting and alarm resetting.
The Total-Volume Infused numerical display permits the nurse to see instantly how much IV solution has been given to the patient, and the Check Point Volume display is set to the total volume prescribed by the physician's orders, so that when the volume has been infused, both the audible alarm sounds and a light begins flashing advising the nurse that it is the correct time to add additional medication.
The optical sensing head unit includes a light emitting diode (LED) or similar small light emitter which causes a light, for example a small red light, to flash each time a drop falls, thereby permitting the nurse to observe from the door of the patient's from the flashing light and thus see that the IV appears to be operating, and by observing the constantly changing numbers on the digital display for infused volume, the nurse is insured that the IV set is working at the proper rate. If blockage occurs, the No-Drop alarm signal is activated and additionally the flashing drop indicating light ceases to flash, instantly advising the nurse of this condition.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.